Enhanced production of curdlan by coupled fermentation system of Agrobacterium sp. ATCC 31749 and Trichoderma harzianum GIM 3.442

Abstract

A coupled fermentation system of Agrobacterium sp. ATCC 31749 and Trichoderma harzianum GIM 3.442 (AT-CFS) with wheat bran as the optimal nitrogen source was established for producing low-molecular-weight curdlan with high production, which can potentially reduce the cost of low-molecular-weight curdlan biosynthesis. The initial inoculate ratio, pH and the fermentation time were optimized. Compared with the curdlan from the single fermentation system of Agrobacterium sp. ATCC 31749 (A-SFS), the molecular weight (Mw) of the curdlan produced from AT-CFS decreased by 34.01% (from 110.85kDa to 73.15kDa), and the curdlan production (47.9g/L) and conversion rate of glucose to curdlan (0.60gg−1) increased by 119.93% and 36.36%, respectively. The results of RT-PCR showed high curdlan production in AT-CFS was highly correlated with aerobic respiration intensity and curdlan synthase activity. The structure of the curdlan from AT-CFS was the same as that from A-SFS.